Boron tribromide → 5-Amino-2-fluorophenol

To a stirred solution of 4-fluoro-3-methoxyaniline (4.80 g, 34 mmol) in dichloromethane (50 mL), at −10° C., was added a 4.0 M solution of boron tribromide in dichloromethane (20 mL, 80 mmol). The reaction mixture was allowed to warm to rt and stirring was continued for a further 15 h. The reaction mixture was quenched via the addition of methanol. After concentration under reduced pressure, the residue was taken up in water, basified with saturated sodium hydrogen carbonate solution, and extracted with ethyl acetate. The combined ethyl acetate layers were washed with brine, dried over MgSO4, and concentrated under reduced pressure to afford 5-amino-2-fluorophenol (4.00 g, 93%) as a solid which was taken on without further purification. 1H NMR (400 MHz, CDCl3) δ 6.87 (dd, J=9.2, 9.2 Hz, 1H), 6.35 (m, 1H), 6.16 (m, 1H), 5.09 (brs, 1H), 3.56 (brs, 2H); LC-MS (ESI) m/z 128 (M+H)+.

1. customThe reaction mixture was quenched via the addition of methanol
2. concentrationAfter concentration under reduced pressure
3. extractionextracted with ethyl acetate
4. washThe combined ethyl acetate layers were washed with brine
5. dry with materialdried over MgSO4
6. concentrationconcentrated under reduced pressure

ORD record

ord-424bc2dddcd541b59bd30abaed2b5308

Source dataset

uspto-grants-2016_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09320739B2